The design and fabrication of miniature microwave bandpass filters using multilayer liquid crystal polymer technology

This thesis presents the design and fabrication techniques for miniature microwave bandpass filters using multilayer liquid crystal polymer (LCP) technology. As a multilayer technology for microwave devices, LCP is of low cost and light weight. It also has excellent electrical properties across a wide frequency range. These characteristics make it promising for the development of next generation microwave devices for applications across commercial, defence and civil sectors. However, very limited work has been found in the open literature to apply this technology to the design of miniature bandpass filters, especially at low microwave frequencies. In addition, the reported work shows lack of fabrication techniques, which limits the size reduction of multilayer LCP devices. To address these problems, this thesis develops advanced fabrication techniques for sophisticated LCP structures, such as multilayer capacitors, via connections and cavities. These techniques are then used to support the design of novel miniature bandpass filters for wideband and narrowband applications. For the design of miniature wideband bandpass filters, a cascaded approach, which combines highpass and lowpass filters, is presented first to provide a flexible design solution. This is followed by another novel ultra-wideband bandpass filter which produces extra transmission zeroes with minimum number of elements. It does not only have high performance but also a compact structure for high yield fabrication. For narrowband applications, two types of advanced coupled-resonator filters are developed. One type produces a very good selectivity at the upper passband edge, and its spurious-free stopband is extremely wide and of high interference attenuation. The other type, based on novel mixed-couplings approaches developed in this thesis, provides a solution to produce almost the same response as the coupling matrix prototype. This type is used to generate arbitrarily-located transmission zeroes. All designs presented in this thesis are simulated using CAD design tools and then validated by measurements of fabricated samples. Good agreements between simulations and measurements are shown in the thesis

Geographic and Climatic Attributions of Autumn Land Surface Phenology Spatial Patterns in the Temperate Deciduous Broadleaf Forest of China

Autumn vegetation phenology plays a critical role in identifying the end of the growing season and its response to climate change. Using the six vegetation indices retrieved from moderate resolution imaging spectroradiometer data, we extracted an end date of the growing season (EOS) in the temperate deciduous broadleaf forest (TDBF) area of China. Then, we validated EOS with the ground-observed leaf fall date (LF) of dominant tree species at 27 sites and selected the best vegetation index. Moreover, we analyzed the spatial pattern of EOS based on the best vegetation index and its dependency on geo-location indicators and seasonal temperature/precipitation. Results show that the plant senescence reflectance index-based EOS agrees most closely with LF. Multi-year averaged EOS display latitudinal, longitudinal and altitudinal gradients. The altitudinal sensitivity of EOS became weaker from 2000 to 2012. Temperature-based spatial phenology modeling indicated that a 1 K spatial shift in seasonal mean temperature can cause a spatial shift of 2.4–3.6 days in EOS. The models explain between 54% and 73% of the variance in the EOS timing. However, the influence of seasonal precipitation on spatial variations of EOS was much weaker. Thus, spatial temperature variation controls the spatial patterns of EOS in TDBF of China, and future temperature increase might lead to more uniform autumn phenology across elevations

Modeling and 3D Simulation of the Mould Compression and Resin Flow for Force-Controlled Compression Resin Transfer Moulding

Since the existence of the complicated coupling between mould compression and resin flow, the full 3D simulation of the filling process in force-controlled compression resin transfer moulding (CRTM) has not been realized, especially when the resin flow front is irregular on the thickness direction during thick part moulding. In this paper, the coupled resin flow and mould compression behaviors are investigated firstly, a equivalent spring method is proposed to describe the preform compaction. The lubrication effect is taken into account, so the mould compression speed can be determined when the resin flow front is irregular on the thickness direction. Then the Volume of Fluid (VOF) two-phase model is established to express the resin-air flow in narrow gap and preform simultaneously, in which the narrow gap is considered as 3D area without flow resistance. Finally, the 3D numerical method for solving the above mathematical models is developed. In this method, the changing of the mould cavity is simulated by moving mesh technology, and the master-slave element method is used to simulate the resin squeezing from the infiltrated preform. Comparisons with analysis results are provided to prove the correctness of the above method, and two 3D examples are given to demonstrate the simulating capability

Pharmacokinetic and Pharmacogenetic Factors Contributing to Platelet Function Recovery After Single Dose of Ticagrelor in Healthy Subjects

Objectives: This study aimed to elucidate the contribution of candidate single nucleotide polymorphisms (SNPs) related to pharmacokinetics on the recovery of platelet function after single dose of ticagrelor was orally administered to healthy Chinese subjects.Methods: The pharmacokinetic profiles of ticagrelor and its metabolite AR-C124910XX (M8), and the platelet aggregation (PA), were assessed after 180 mg of single-dose ticagrelor was orally administered to 51 healthy Chinese subjects. Effects of CYP2C19*2, CYP2C19*3, CYP3A5*3, UGT1A1*6, UGT1A1*28, UGT2B7*2, UGT2B7*3, SLCO1B1 388A>G, and SLCO1B1 521T>C, on the pharmacokinetics of ticagrelor and M8, and platelet function recovery were investigated.Results: The time to recover 50% of the maximum drug effect (RT50) ranging from 36 to 126 h with 46.9% CV had a remarkable individual difference and was positively associated with the half-life (t1/2) of M8 (r = 0.3901, P = 0.0067). The time of peak concentration (Tmax) of ticagrelor for CYP2C19*3 GG homozygotes was significantly higher than that of GA heterozygotes (P = 0.0027, FDR = 0.0243). Decreased peak concentration (Cmax) of M8 was significantly associated with SLCO1B1 388A>G A allele (P = 0.0152, FDR = 0.1368). CYP2C19*2 A was significantly related to decreased Cmax of M8 (P = 0.0455, FDR = 0.2048). While, the influence of these nine SNPs on the recovery of platelet function was not significant.Conclusion: Our study suggests that the elimination of M8 is an important factor in determining the recovery of platelet function. Although CYP2C19 and SLCO1B1 genetic variants were related to the pharmacokinetics of ticagrelor or M8, they did not show a significant effect on the platelet function recovery in this study.Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT03092076, identifier: NCT0309207

Quantity and clinical relevance of circulating endothelial progenitor cells in human ovarian cancer

<p>Abstract</p> <p>Background</p> <p>Circulating bone marrow-derived endothelial progenitor cells (EPCs) have been reported to participate in tumor angiogenesis and growth; however, the role of circulating EPCs in tumor progression is controversial. The role of circulating EPCs in ovarian cancer progression and angiogenesis has not yet been investigated.</p> <p>Methods</p> <p>The number of circulating EPCs in the peripheral blood in 25 healthy volunteers and 42 patients with ovarian cancer was determined by flow cytometry. EPCs were defined by co-expression of CD34 and vascular endothelial growth factor receptor 2 (VEGFR2). In addition, we determined CD34 and VEGFR2 mRNA levels by real-time reverse transcription-polymerase chain reaction. Plasma levels of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) were determined by enzyme-linked immunosorbent assay.</p> <p>Results</p> <p>Circulating levels of EPCs were significantly increased in ovarian cancer patients, correlating with tumor stage and residual tumor size. Higher levels of EPCs were detected in patients with stage III and IV ovarian cancer than in patients with stage I and II disease. After excision of the tumor, EPCs levels rapidly declined. Residual tumor size greater than 2 cm was associated with significantly higher levels of EPCs. In addition, high circulating EPCs correlated with poor overall survival. Pretreatment CD34 mRNA levels were not significantly increased in ovarian cancer patients compared with healthy controls; however, VEGFR2 expression was increased, and plasma levels of VEGF and MMP-9 were also elevated.</p> <p>Conclusions</p> <p>Our results demonstrate the clinical relevance of circulating EPCs in ovarian cancer. EPCs may be a potential biomarker to monitor ovarian cancer progression and angiogenesis and treatment response.</p

Seasonal peak photosynthesis is hindered by late canopy development in northern ecosystems

Altres ajuts: Fundación Ramón Areces grant CIVP20A6621.The seasonal dynamics of the vegetation canopy strongly regulate the surface energy balance and terrestrial carbon fuxes, providing feedbacks to climate change. Whether the seasonal timing of maximum canopy structure was optimized to achieve a maximum photosynthetic carbon uptake is still not clear due to the complex interactions between abiotic and biotic factors. We used two solar-induced chlorophyll fuorescence datasets as proxies for photosynthesis and the normalized diference vegetation index and leaf area index products derived from the moderate resolution imaging spectroradiometer as proxies for canopy structure, to characterize the connection between their seasonal peak timings from 2000 to 2018. We found that the seasonal peak was earlier for photosynthesis than for canopy structure in >87.5% of the northern vegetated area, probably leading to a suboptimal maximum seasonal photosynthesis. This mismatch in peak timing signifcantly increased during the study period, mainly due to the increasing atmospheric CO2, and its spatial variation was mainly explained by climatic variables (43.7%) and nutrient limitations (29.6%). State-of-the-art ecosystem models overestimated this mismatch in peak timing by simulating a delayed seasonal peak of canopy development. These results highlight the importance of incorporating the mechanisms of vegetation canopy dynamics to accurately predict the maximum potential terrestrial uptake of carbon under global environmental change

Neural Speaker Diarization Using Memory-Aware Multi-Speaker Embedding with Sequence-to-Sequence Architecture

We propose a novel neural speaker diarization system using memory-aware multi-speaker embedding with sequence-to-sequence architecture (NSD-MS2S), which integrates the strengths of memory-aware multi-speaker embedding (MA-MSE) and sequence-to-sequence (Seq2Seq) architecture, leading to improvement in both efficiency and performance. Next, we further decrease the memory occupation of decoding by incorporating input features fusion and then employ a multi-head attention mechanism to capture features at different levels. NSD-MS2S achieved a macro diarization error rate (DER) of 15.9% on the CHiME-7 EVAL set, which signifies a relative improvement of 49% over the official baseline system, and is the key technique for us to achieve the best performance for the main track of CHiME-7 DASR Challenge. Additionally, we introduce a deep interactive module (DIM) in MA-MSE module to better retrieve a cleaner and more discriminative multi-speaker embedding, enabling the current model to outperform the system we used in the CHiME-7 DASR Challenge. Our code will be available at https://github.com/liyunlongaaa/NSD-MS2S.Comment: Submitted to ICASSP 202

Three-dimensional pseudocontinuous arterial spin labeling perfusion imaging shows cerebral blood flow perfusion decline in attention-deficit/hyperactivity disorder children

PurposeTo investigate the feasibility of three-dimensional pseudocontinuous arterial spin labeling (3D-pcASL) perfusion imaging in the brain of children with Attention-deficit/hyperactivity disorder (ADHD).MethodsA total of 78 ADHD children aged 5–13 years were prospectively selected as the study group, and 89 healthy children matched in age and sex were selected as the control group. All children underwent MRI conventional sequence, 3D-pcASL, and 3D-T1 sequence scans. The brain gray and white matter volume and cerebral blood flow (CBF) perfusion values were obtained by software post-processing, and were compared and analyzed in the two groups to find out their characteristics in the brain of ADHD children.ResultsThe total brain volume and total CBF values were lower in ADHD children than in healthy children (P &lt; 0.05); the gray and white matter volumes in the frontal lobe, temporal lobe, hippocampus, caudate nucleus, putamen, globus pallidus and other brain regions were lower in ADHD children than in healthy children (P &lt; 0.05); the gray matter CBF values in the frontal lobe, temporal lobe, hippocampus, caudate nucleus, putamen, globus pallidus and other brain regions were lower in ADHD children than in healthy children (P &lt; 0.05); the differences between the white matter CBF values of white matter in the said brain regions of ADHD children and healthy children were not statistically significant (P &gt; 0.05); and the CBF values in frontal lobe and caudate nuclei could distinguish ADHD children (AUC &gt; 0.05, P &lt; 0.05).ConclusionThe 3D-pcASL technique showed reduced cerebral perfusion in some brain regions of ADHD children

Causal associations of genetically predicted gut microbiota and blood metabolites with inflammatory states and risk of infections: a Mendelian randomization analysis

BackgroundInflammation serves as a key pathologic mediator in the progression of infections and various diseases, involving significant alterations in the gut microbiome and metabolism. This study aims to probe into the potential causal relationships between gut microbial taxa and human blood metabolites with various serum inflammatory markers (CRP, SAA1, IL-6, TNF-α, WBC, and GlycA) and the risks of seven common infections (gastrointestinal infections, dysentery, pneumonia, bacterial pneumonia, bronchopneumonia and lung abscess, pneumococcal pneumonia, and urinary tract infections).MethodsTwo-sample Mendelian randomization (MR) analysis was performed using inverse variance weighted (IVW), maximum likelihood, MR-Egger, weighted median, and MR-PRESSO.ResultsAfter adding other MR models and sensitivity analyses, genus Roseburia was simultaneously associated adversely with CRP (Beta IVW = −0.040) and SAA1 (Beta IVW = −0.280), and family Bifidobacteriaceae was negatively associated with both CRP (Beta IVW = −0.034) and pneumonia risk (Beta IVW = −0.391). After correction by FDR, only glutaroyl carnitine remained significantly associated with elevated CRP levels (Beta IVW = 0.112). Additionally, threonine (Beta IVW = 0.200) and 1-heptadecanoylglycerophosphocholine (Beta IVW = −0.246) were found to be significantly associated with WBC levels. Three metabolites showed similar causal effects on different inflammatory markers or infectious phenotypes, stearidonate (18:4n3) was negatively related to SAA1 and urinary tract infections, and 5-oxoproline contributed to elevated IL-6 and SAA1 levels. In addition, 7-methylguanine showed a positive correlation with dysentery and bacterial pneumonia.ConclusionThis study provides novel evidence confirming the causal effects of the gut microbiome and the plasma metabolite profile on inflammation and the risk of infection. These potential molecular alterations may aid in the development of new targets for the intervention and management of disorders associated with inflammation and infections